The past participle is parked.
Answer: I had gone to the park.
Park can be a verb or a noun. As a verb you would "Park the car." As a noun you would "Take the kids to the park."
The past participle of "am not" is "have not been."
The past participle of "do" is "done." The past participle of "have" is "had."
The past tense of "have" is "had," and the past participle is also "had."
The past and past participle for "buy" is "bought."
Being is the present participle. The past participle is been.
Eating is the present participle; eaten is the past participle.
The past participle is thought.
"Did" is the past and "done" is the past participle.
The past participle is had.
The past participle of "do" is "done."